Formation of filaments directly from molten material

ABSTRACT

A METHOD FOR PRODUCING CONTINUOUS OR CONTROLLED LENGTH DISCONTINUOUS PRODUCTS HAVING A SMALL CROSS-SECTIONALS AREA SUCH AS FILAMENTS OR WIRE DIRECTLY FROM A POOLLIKE SOURCE OF MOLTEN METAL OR A MOLTEN INORGANIC COMPOUNDS HAVING A SURFACE TENSION AND VISCOSITY SIMILAR TO THAT OF A MOLTEN METAL CONSISTING OF FORMING SUCH PRODUCTS BY THE APPLICATION OF A ROATING DISK-SHAPED MEMBER TO THE SURFACE OF THE POOL OR MOLTEN MATERIAL SO AS TO FORM THE MATERIAL INTO THE DESIRED SHAPE BY EXTRACTING A FILAMENTARY FORM OF MATERIAL FROM THE SUPPLY OF MOLTEN MAT2 TERIAL. THE FINAL SHAPE OF THE PRODUCT IS DETERMINED BY THE PHYSICAL SHAPE OF THE MEMBER, THE TEMPERATURE AND MATERIAL COMPOSITION OF THE MELT. AS WELL AS THE VELOCITY OF THE MEMBER IN CONTACT WITH THE MELT. THE INVENTION DOES NOT RELY ON ANY TYPE OF ORIFICE OR THE MECHANICAL REMOVAL OF THE PRODUCT FROM THE MOVING MEMBER.

l 1.74 R. E. MARINGER E AL 3,838,185

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FORMATION OF FI'LAMEN'IS DIRECTLY FROM MOIJTEN MA'IERIAL Filed May 10. 1972 5 Sheets-Sheet 2 Fig.6

Sept. 24, R. E. MARINGER ETA L 3,838,185

FORMATION OF FILAMENTS DIRECTLY FROM MOLTEN MATERIAL Filed May 10. 1972 C5 Sheets-Sheet 5 limited States Tatent O 3,838,185 FORMATION OF FILAMENTS DIRECTLY FROM MOLTEN MATERIAL Robert E. Maringer, Worthington, Ohio, Alfred Rudnick, Tel Aviv, Israel, and Carroll E. Mobley, Columbus, Ohio, assignors to Battelle Development Corporation, Columbus, Ohio Continuation-impart of abandoned application Ser. No. 147,390, May 27, 1971. This application May 10, 1972, Ser. No. 251,985

Int. Cl. Btllj 2/02 U.S. Cl. 2648 19 Claims ABSTRACT OF THE DISCLOSURE A method for producing continuous or controlled length discontinuous products having a small cross-sectional area such as filaments or wire directly from a poollike source of molten metal or a molten inorganic compound having a surface tension and viscosity similar to that of a molten metal consisting of forming such products by the application of a rotating disk-shaped member to the surface of the pool or molten material so as to form the material into the desired shape by extracting a filamentary form of material from the supply of molten material. The final shape of the product is determined by the physical shape of the member, the temperature and material composition of the melt as well as the velocity of the member in contact with the melt. The invention does not rely on any type of orifice or the mechanical removal of the product from the moving member.

Cross-Reference to Related Application The present application is a continuation-in-part of Ser. No. 147,390 filed May 27, 1971, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a method capable of the continuous production of a filament or wire, directly from a pool-like supply of molten material by the use of a rotating disk in contact with that molten material and without the use of a forming orifice.

The conventional method of producing metal products of small cross section such as wire involves the casting of billets and their subsequent formation into the final product by mechanical Working that may include extrusion, drawing, rolling, and other normal mechanicalforming techniques. In addition to these numerous postcasting mechanical operations there may be the necessity of intermittent heat treatment beforethe intermediate product can be further mechanically worked. The cost of these subsequent operations has created a long standing search for a means to form small cross-section continuous products directly from the molten metal.

The prior art methods used to make such products as filament or wire from inorganic compounds are substantially different since inorganic compounds do not have the mechanical properties to withstand forming processes as used on metallic materials. The formation of compounds into final shapes is usually carried out while the material is molten such as casting directly into a forming mold. The subject invention forms the desired product directly from the molten state, and therefore, inorganic compounds having properties in the molten state similar to that of molten metals and metal alloys may be formed in substantially the same manner. The properties that must be similar to that of molten metal are the viscosity and surface tension in the molten state as well as the compound having a substantially discrete melting point rather than a broad continuous range of viscosities characteristic of molten glasses.

ice

Materials conforming to the class having such properties will have a viscosity in the molten state when at a temperature less than percent of their melting point in degrees Kelvin in the range from 10- to 1 poise as Well as having surface tension values in that same temperature range in the order of from 10 to 2500 dynes/cm.

Prior art patents and publications show many methods for producing metallic wire using a rotating disk-like surface. The processes typically have molten metal flowing out an orifice determining the size of the final product. U.S. Pat. 745,786, Cole, is typical of the prior art devices where the disk-like surface is a rotating metallic wheel upon which molten metal is impinged by way of an orifice. The prior art methods of producing wire products use flow conditions varying from the removal of the metal from a stable meniscus disclosed in U.S. Pat. 3,522,- 836, King, to the forcing of molten metal in a free-standing stream through the orifice directly on a rotating heatextracting surface as disclosed by U.S. Pat 2,825,108, Pond. The prior art means of direct formation of a filament or wire-like product all have one feature in common-the use of an orifice to control the size and flow of the molten metal.

The use of an orifice has several attendant difiiculties in that it must function in the severe environment of flowing molten metal. Where the metal product desired is composed of low melting point alloys such as lead, tin, zinc, etc., the problems with the orifice are not severe. However, due to the commercial demand to make a continuous product out of materials having relatively high melting points, processes using orifices are plagued with several difficult problems.

At higher temperatures, orifice materials begin to react with the molten metal or the surrounding atmosphere degrading the properties of the orifice material as well as its physical dimensions. Consequently, the orifice tends to erode and wash, becoming larger, and providing out of gage products. Further, insoluble materials such as silicates or refractory particles from the refractory container tend to clog orifices particularly where fine gage products are involved. As a consequence, the usual materials for orifices which resist erosion are expensive and difiicult to form into the shape needed for the application; and, once formed, the erosion due to the flowing metal makes the size of the final product difiicult to control.

The use of an orifice usually requires additional heating to insure that metal does not solidify in the orifice and thereby change the shape of the product formed. The use of small orifices requires extremely clean melts to prevent intermittent plugging or restriction of the orifices.

The present method invention forms a filamentary product without the use of any type of orifice and, therefore, is free of all problems attendant the flow of molten metal through an orifice. The size of the final product is controllable and is primarily affected by the shape and properties of the rotating disk applied to the surface of a molten pool, its heat-extracting properties, its depth of entry into the melt, its velocity in contact with the melt, the melt superheat, and the melt material.

BRIEF SUMMARY OF THE INVENTION The invention as herein disclosed is a method for producing continuous or controlled length discontinuous filaments directly from a pool-like supply of molten material. The method invention uses a rotating disk-shaped memher having an axis of rotation substantially parallel to the surface of a molten pool of the material.

Broadly stated, the invention provides a method for producing a solid filament from molten material normally solid at ambient temperature having properties in the molten state at their conventional casting temperatures substantially similar to molten metals by the steps of introducing the outer edge of a rotating disk-shaped member to the surface of a pool of molten material, controlling the contact area and time of contact of said edge in said pool so that the maximum cross sectional dimension of said filament is greater than the cross section of said edge parallel to the axis of rotation at the average depth of immersion of the edge, removing heat at the circumferential extremity of said member to cause solidification of said material in filament form on said member and allowing said final filamentary product to spontaneously release from said member.

For the purposes of this invention a pool or pool-like source of molten material is one that is not confined by a limiting orifice and has a free surface relatively free of turbulence. Turbulence does not prevent operation of the process, but makes the quality of the product somewhat irregular. As the invention is practiced, flow induced by induction heating of the melt does not detrimentally affect the process. In fact, the productivity of the process may be enhanced by flowing molten material parallel to the direction of rotation of the rotating member and increasing the speed of rotation of the member. Generally flow directed across the member will disturb the filament formation if the magnitude of the flow is sutficiently large.

When the periphery of the rotating disk is introduced to the surface of the melt, a portion of the melt solidifies on the member and is carried through the melt by the rotation. This rotation also initiates a buildup of molten material above the equilibrium level of the melt immediately adjacent the point where the member exits the melt. Molten material from this buildup is at a slightly lower temperature than the melt and adheres to the previously formed material on the edge of the rotating member and exiting the melt through. this buildup. The form of the final product is determined by the portion of material initially solidified on the member as well as the liquid portion deposited on the solidified portion as it passes through the buildup of material upon exiting from the pool of molten material.

If the rotating disk member is raised after the process has been initiated, a continuous product can be produced by passing the disk through this buildup of molten material without having an initially solidified product on the surface of the disk before entering the buildup. In fact, the periphery of the disk may be above the equilibrium level of molten material and pass only through the aforementioned buildup of molten material.

The essence of the present invention resides in a method of extracting molten material from the surface of a molten pool by contacting such surface with the edge of a rotating disk. Although the disk may act at least in part as a heatextracting member or chill block, its essential function is extracting the molten material from the molten pool in continuous or semicontinuous fashion into the surrounding atmosphere or controlled gaseous environment where quenching occurs. It is our belief that a film of molten material initially wets the surface of the rotating disk and thus clings to such surface as it passes from contact with the molten material. As cooling progresses the thin filament contracts, separates from the disk surface, and is ejected into the surrounding gaseous environment by the uninhibited centrifugal force of the rotating disk where solidification of any liquid portion with the film is completed. Since the disk presents a limited contact area and rotates at relatively high speed the product is thin gage wire or filament rather than heavy gage material attained in prior art processes.

The shape of the final product is dependent in part on the shape of the rotating disk introduced to the melt surface. In the production of filaments or wire-like material the periphery of the shell is V-shaped or radiused with only the tip of the member being introduced to the surface of the molten material.

For the purposes of this invention, a wire or filament shall be defined as an elongated member having a crosssectional area less than .020 in. and a width measurement less than 0.20 in.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of the apparatus producing a filamentary product in accordance with one method of the present invention.

FIG. 2 is a vertical section of the melt container of FIG. 1 showing the spinning disk producing a fiber or filament from a buildup of molten material above the equilibrium surface level of the melt.

FIG. 3 is a vertical cross section of the apparatus of FIGS. 1 and 2 showing the shape of the disk-like member used to produce fiber or filament with that member introduced to the melt below its equilibrium surface level.

FIG. 4 shows an enlarged cross section of the tip of a disk-like member in a melt illustrating the physical dimensions that effect the properties of filamentary products.

FIG. 5 is a cross-sectional view of a disk-like member that is kept at substantially constant temperature by the internal circulation of a liquid coolant.

FIG. 6 shows two views of a disk-like member that produces filaments having a controlled length.

FIG. 7 shows a cross section of a radiused disk-like member in a melt showing such a member as used for the production of filament.

FIG. 8 shows a partial cross section of a multiple edge disk-shaped heat-extracting member.

DETAILED DESCRIPTION OF THE INVENTION The means by which the process of making a filamentary product is illustrated in one configuration in FIG. 1. For the forming of a filamentary product, a disk 3th is rotated by its attachment through some type of power transmission device such as the shaft 35 to a rotating motor herein disclosed as an electric motor 40. The motor 40 is mounted on a platform 41 that is capable of being adjusted vertically through the use of a jack 45. This vertical adjustment should not be accomplished by any substantial rotation around the axis of the jack 45 since this would affect the direction of the emission of the filament 20. The placement of the jack base 4-7 is not critical and the process is not adversely affected by minor misalignments or deviations from the true vertical. While minor natural vibrations from the rotation of the apparatus do not seem to adversely affect the process, and the process has been successfully employed without using damping materials under the base 47, the quality of the filament is enhanced by the elimination of vibration. The electric motor 40 should have some method of controlling its rotational speed and, as illustrated, the apparatus is equipped with a rheostat-type control 42. The motor support plate 41 may be extended toward the disk 30 to provide a support for a shaft bearing (not shown) if the length of the shaft 35 and the size of the disk 30 pose alignment or vibrational problems. It would also be possible to extend the shaft 35 through the disk 30 to the other side to another support bearing (not shown). For most applications the shaft 35 is substantially parallel to the surface 15 of the melt 10; however, this angle may be acute with no substantial detriment to the process. In some applications such as the formation of discontinuous fiber, it may be advantageous since centrifugal force would then eject the fibers away from the melt rather than straight up above the melt only, to fall back in and possibly disturb the process. The disk 30 must introduce a relatively narrow surface to the melt 10 to form a filamentary product 20, but the exact shape of the surface will be discussed with other process parameters; however, in general a nonreplicating filament 20 will emanate from a disk 30 that rotationally introduces a small area 32 of its circumference having substantially line contact with the surface of the melt 10 or to a buildup of molten material above the surface. When the disk-shaped member introduces only a small chord length of its peripheral edge, its contact with the melt is narrow and elongated in the direction of the filament length and is best described as a line contact. This line contact promotes solidification on a narrow area 32 on the member 30 and the direction of heat removal solidifies filamentary form that is not simply a female replica of the peripheral edge introduced to the surface of the melt 10. The process Will become unstable when the melt raises the temperature of the area 32 to a degree where the solidification rate is significantly retarded and the area 32 is removed from the melt 10 before any significant solidification can form a filament 20' on the area 32 as shown in FIGS. 2, 3, and 4. We have found that surprisingly the rotating member can pass through the melt at speeds up to 200 ft./sec. and still promote solidification. Fully realizing the following range may be defined by equipment rather than process limitations, it has been found that the preferred range of operating speeds is from 5 to 100 ft./sec.

Normally filament is formed in the melt by controlling the area of contact of the rotating member as well as its contact time with the molten material so that the typical cross sectional dimension of the filamentary product is less than .060 inches but greater than the width of the cross section of the edge introduced to the molten material as measured parallel to the axis of rotation of the member at the average depth of immersion of the edge of the rotating member. Referring to FIG. 4, the width of 20, and subsequently 20, will be greater than the width of the radiused portion of the member 30 at r.

The supply of molten material referred to as the melt 10 may be composed of an elemental metal, metal alloy, or an inorganic compound heated and contained by a vessel 11 having elements 12 to heat the material contained to a temperature above its melting point. While the amount of superheat (number of degrees in excess of the materials equilibrium melting point) will affect the size or gage of the filament 20, we have found that substantially constant diameter filaments 20 can be produced with a melt at a temperature less than 125 percent of the equilibrium melting point (in K.) of the material used with no need for the precise control of the melt temperature during operations. While this quantitative definition of the preferred temperature will normally encompass the desired melt temperature, it should be understood that the process does not require unusual melt temperatures. Therefore, the process is known to be operable with metals and metal alloys at conventional casting temperatures that represent a compromise between the cost of heating versus fluidity of the molten material. The melt 10 may have a thin protective flux coating to prevent excessive reaction with the surrounding atmosphere without substantially disturbing the formation of the filament 20. The filament is initially formed, as illustrated in FIGS. 2 and 3, below a surface of the melt 10 and will pass through most surface fluxes without any adverse etfects. Where it is desired or necessary, the simplicity of the apparatus lends itself to the use of a simple container (not shown) for the process where the atmosphere surrounding the melt 10 and the filament 20 while it is still at high temperatures can be kept inert.

Filamentary material has been successfully produced from several metals and metal alloys including tin, zinc, copper, nickel, aluminum, aluminum alloys, aluminum bronze, cast iron, ductile iron, high and low carbon steel, 18-8 stainless steel, and Hadfield steel. While these materials are known to be readily formed into filaments by the subject invention, the present invention is obviously applicable to a wider range of molten materials. The present process may be used with any material having several specific properties similar to those of a molten metal, i.e., having a low viscosity in the range of from 1O to 1 poise, a high surface tension in the range of from 10 to 2500 dynes/cm., a reasonably discrete melting point, and being at least momentarily compatible with a solid material having sufficient heat capacity or thermal conductivity to initiate solidification on the outer edge 32 of the disk 30 made of that solid material. For the purposes of this invention, a reasonably discrete melting point shall be defined as one exhibited by materials changing state from liquid to solid, changing state of one alloy component passing through a liquidus line on a temperaturecomposition phase diagram, or any change in state exhibiting a discontinuous viscosity increase upon reduction of melt temperature. Filamentary products have been produced from a molten alkali nitrate heat-treating salt known commercially as Houghtons Draw Temp 430 available from E. F. Houghton & Company, Philadelphia, Pa., which is typical of inorganic compounds having the aforementioned properties in the molten state.

The disk 30 as shown in FIGS. 1 through 4 has a configuration that produces continuous metallic filaments 20 from the melt 10. FIGS. 2 and 3 show two different orientations of the disk 30 with relation to the melt 10 while FIG. 4 illustrates the dimensions of the outer portions 31 of the disk 30. Referring now to FIGS. 1 and 3, the disk 30 is rotated within the melt 10 just below its surface 15, and subsequent to its entry into the melt 10 at 13 the disk 30 nucleates solid metal on the edge 32 of the disk 30 not necessarily at point 13 by removing the superheat and the heat of fusion of the melt 10. During the rotation of the disk 30 the melt 10 continues to solidify on the disk edge 32 forming the filament 20'. The size of the final filament 20 is determined by the size and shape of the imposed disk surface 32 and the amount of heat removed by the disk 30. The amount of heat removed, therefore, depends on several controlled vari ables, one of which is the residence time of a point on the disk edge 32 within the melt 10 which is a function of the distance along the disk edge 32 from point 13 to 14 and the speed of rotation of the disk 30. The size of the final filament 20 is determined by the amount of molten material 1t) that is deposited on 20' when it passes through the buildup of molten material 16.

Another variable affecting heat removal is the shape of the disk edge 32. It must nucleate and grow a filamentary product yet dissipate enough heat to maintain it at a temperature below that of the melt 10. The amount of this temperature differential will be discussed in a subsequent portion of the disclosure. The shape of the disk 30 as illustrated in FIG. 4 shows the physical dimensions that affect the rate of heat removal. The disk 30 is inserted into the melt 10 at a depth shown in the figure as d. While the process is operable to form replicating strip-like products at large values of d, filamentary products are most efliciently produced when the value of d is less than .060 inches and yields a filamentary product less than .010 in. in cross sectional area.

For some applications, this value of d remains substantially constant through the entire process; however, the process is operable for some materials with the edge of disk 30 at or above the equilibrium surface level 15 passing through a buildup of molten material 61 generated by rotation of the member 30. When the process is carried out in that manner, the buildup 16 is generated by initially rotating the member 30 below the surface 15 of the melt as shown in FIG. 3. The member 30 is then slowly raised until it contacts the melt only at that buildup of molten material 16 at the exit side of the rotating member.

The radius of curvature r at this disk edge 32 will affect the final form of the filament 20 since it is essentially a mold for one side of the filament 20' as well as providing the site for initial nucleation of 20'. Filaments have successfully been produced with r ranging from .015 inch to co (i.e., a narrow, fiat projection into the melt 10). A preferred embodiment would have r within the range of from .001 to 0.10 inches. In addition to the V-shaped configuration, a member 30 having a radiused peripheral edge may also be used. A filamentary product is formed with such a member if the depth of insertion is less than 0.020 and the radius of curvature is less than .50 inches. All of edges 32 of the member 30 have a common characteristic in that they are all rounded or in some way relieved and a change in cross sectional direction so as to freely release any product solidified thereon. The variables 0, T, and D as shown in FIG. 4 affect the conductivity of the heat emanating from 32 to the cooler portions of the disk 30. These variables are controlled by the chill material and any form of external cooling of the disk 30. The manipulation of these variables is not critical and one skilled in the art can successfully arrive at a workable configuration without excessive trial and error. The value of R affects the process in two ways, one of which is affecting the mass of the member 30 and hence its thermal capacity. The thermal capacity of the disk 30 can be controlled by material selection, external cooling, and the manipulation of the variables 0, T, and D; therefore, variation of R is not primarily used to control the total thermal capacity of the disk 30. R does, however, directly affect several important process variables; namely, the aforementioned residence time of a point on the disk edge 32 within the melt 10 and the generation of centrifugal forces that affect the spontaneous removal of the filament 20 from the disk 30 at point 25. Various disks 30 having a radius as small as fit-inch (the end of a rotating rod introduced at an angle to the melt) and as large as inches have successfully been used to produce a filament without any indication of their being the minimum or maximum feasible radii defining a critical range of disk sizes.

It is felt that the process is not inherently limited as to the maximum size of the disk, but a practical limit would seem to be a disk having a radius greater than inches. With disks having a radius greater than this value, the residence time in the melt becomes excessive as well as reducing the centrifugal force critical for spontaneous product removal. Several different disks 30 have been successfully used to produce a filament including the configuration shown in FIGS. 1 through 4. In addition, a thin circular disk 30 having a flat peripheral edge 32 and a thickness of .0625 inch produced continuous metallic fiber for a few seconds until the heat of the melt 10 increased the temperature of the disk 30 to the point where there was no formation of a filament 20'. The temperature difference between the disk edge 32 and the melt 10 affects the process; however, substantial variations in that temperature difference may be tolerated before the effect is noticeable. During the process the disk 30 may start initially at room temperature and after several minutes of operation immersed in molten iron still produce continuous filaments of substantially the same diameter. Eventually the limited thermal capacity of the disk 30 allows the temperature at the disk edge 32 to increase to the point the process is no longer forming a continuous fiber. FIG. 5 shows a disk 30 having the means to circulate a coolant within the disk 30 thereby keeping the disk 30 and the disk edge 32 at a constant temperature once thermal equilibrium is established. The means by which the coolant flow rate is determined is readily discernible to one skilled in the art since the process is operable within a broad range of disk temperatures.

The product as it leaves the disk 30 in some cases will not be completely solid and will consist of a solid film that was formerly adjacent to the disk 30 and a liquid portion that is carried out of the source of molten material by this solid portion. Depending on the thermal capacity of the disk 30 and the point where the filament leaves contact with the disk, the product may continue to solidify or if its liquid portion possesses enough mass and superheat, it may remelt the entire filament after it leaves the thermal influence of the disk 30. Proper adjustment of parameters may result in this fully molten condition long enough to reform the filament into a circular cross section by the effect of the materials high surface tension. The gaseous environment of the filament 20 is important to this type of process since the filament cannot be completely molten for a significant period of time without breaking down into globules. Gaseous coolants such as air or nonoxidizing gases such as nitrogen or argon may be used either solely or in conjunction with a fog or mist of liquid coolant.

The process of making a continuous filamentary product is also applicable to the production of filament in controlled lengths. FIG. 6 illustrates a disk 30 having a plurality of indentations 34 along the disk edge 32. The function of these indentations is to disturb the formation of the filament 20' on the disk edge 32 sufliciently to produce a discontinuous product of a length equal to the distance along the disk edge 32 between successive indentations 34. The shape of the indentations 34 that has successfully produced a discontinuous filament is essentially in the form of a slanted V as shown in FIG. 6. Undoubtedly other indentation shapes would also work. The slanted V-shape has proved to limit effectively the length of the filament while not accumulating solidified metal in the indentation 34 that would eventually affect the intended function of the indentations 34. Since the distance along the disk edge 32 between successive indentations 34 controls the length of the filaments produced, the spacing of these indentations can be controlled to produce short filaments of equal length, a controlled distribution of filament lengths, or a series of longer filaments with a length limited to the circumference of the disk 30 by the use of a single indentation 34. The presence of the indentations 34 enables the disk to be rotated at higher speeds and at a smaller insertion into the melt, with the only other difference being the discontinuous final product 20 and the indentations 34 on the disk edge 32.

The parameters that are herein disclosed to affect the process need not be controlled precisely and the production of a filamentary metal product 20 will result from the introduction of a relatively small area 32 on the periphery of a rotating disk 30 to a pool of molten metal 10 when the disk 30 has a peripheral speed in the range of 3 ft./ sec. to 200 ft./sec. and has sufficient temperature difference to solidify at least a rudimentary filament 20 on the disk edge 32. To start the process, the disk 30 is rotated above the melt 10 at the desired speed to give a peripheral speed within the desired range. The jack 45 is adjusted to lower the disk 30 into the melt 10 where initially a fragmented filament is formed upon contact with the surface 15. The disk 30 is lowered into the melt 10 and upon the disk 30 reaching sufficient depth within the melt 10 a continuous product 20 will emanate from the melt 10 in substantially the manner illustrated in FIGS. 1 and 3. As previously described, it is also possible to raise the disk 30 to or above the equilibrium surface 15 after a filament 20 is bein produced and thereafter pass the periphery of the disk 30 through a buildup of molten material 16 to form a filament 20.

FIG. 7 illustrates another embodiment of the present invention where the disk edge 32 is radiused and inserted into the molten material at a depth less than .020 inch so as to form a filamentary product. If the product to be formed by this embodiment is to be filamentary, then the radius of curvature at the edge 32 should be less than 0.50 inch.

FIG. 8 illustrates an embodiment of the invention where the disk-shaped rotating heat-extracting member has multiple edges in contact with the molten material thereby producing multiple filaments.

The present invention was used in several configurations to form filamentary products from various materials. In the following examples the surface of the disk that contacts the melt consistently has a 16 to 20 micro-inch CLA (center line average) surface finish produced by 600 grit paper, and, except where noted, the depth of insertion of the disk within the melt was approximately 10 mils.

Example 1 A continuous filamentary product was produced using a. copper disk having a V-shaped peripheral edge and having the following physical dimensions:

Diameter of the disk inches 8 Thickness do 1 Radius at the tip of the V do 0.025 Angle of the V, 6 degrees 90 The same disk was used to produce a nickel-base alloy filament by rotating the disk at 400 r.p.m. giving the disk a peripheral speed of 14 ft./sec. The nickel alloy (3 Al, balance Ni) was at a temperature of 2700 F. during the process and continuous filament 6 mils by 35 mils was productd.

Example 4 A continuous filamentary product of zinc was produced by using an aluminum disk having substantially the same V-shaped periphery as the copper disk but having the following dimensions:

Diameter of the disk inches 5.84 Thickness do .5 Radius at the tip of the V do .025 Angle of the V, degrees 90 The disk was rotated at 290 r.p.m. giving a peripheral speed of 7.4 ft./sec. The melt was commercially pure zinc at a temperature of approximately 850 F. The disk operated at a temperature ranging from 140 F. to 300 F. and its rotation produced a continuous filament 7 x 17 mils in cross section.

Example The same disk and melt material were used to produce a continuous filament with a speed of disk rotation of 700 r.p.m. At the peripheral speed of 17.9 ft./sec. the disk was introduced to the surface of the melt at approximately 850 F. The disk operated at a temperature ranging from 200 F. to 410 F. and produced a filament with a cross section of 10 mils x 30 mils.

Example 6 The same disk was used to produce filaments from a molten inorganic compound. The compound was an alkali metal nitrate salt used commercially in the molten condition as a heat-treating bath. Its commercial name is Houghtons Draw Temp 430 made by E. F. Houghton & Company in Philadelphia, Pa. This compound was heated to approximately 450 F. and the disk was introduced to its surface at 240 r.p.m. (6.1 ft./sec.). The disk operated in the range of 80 F. to 200 F. during the process and filaments of 12 mils by 30 mils in cross section were produced.

10 Examples 7 and 8 Continuous aluminum (1100) and aluminum alloy (2024) fiber were produced using a copper disk having a V-shaped peripheral edge and the following physical dimensions:

Diameter of the disk inches 4.8 Thickness do .48 Angle of the V, 0 degrees 109 Radius at the tip of the V inches .010

Both products were made at a disk speed of 1000 r.p.m. and 20.7 ft./ sec. with the aluminum 1100 molten at 1250 F. and the 2024 at 1400 F. In both cases the disk operated at approximately 200 F. and produced filament of a cross section 6 mils by 15 mils.

Example 9 The present invention was used to produce a discontinuous filament of controlled length by using a copper disk having indentations on its V-shaped peripheral edge. The disk had the following physical dimensions.

Diameter of the disk inches 4 Thickness do .47 Radius at the tip of the V do .015 Angle of the V, 6 degrees The disk also had indentations on its peripheral edge substantially the same as those shown in FIG. 6 with the depth of the indentation being approximately 0.03 inches and having a length along the circumference of the disk of 0.15 inches. The disk was rotated at 700 r.p.m. yielding a peripheral speed of 12.1 ft./sec. It was introduced to the surface of a pool of molten zinc at 890 F. and the disk operated within a temperature range of F. to 200 F. A filamentary product having a cross section 8 mils by 16 mils and consistent lengths of approximately 1 inch was formed.

Example 10 The same disk and melt material were used with the melt temperature and disk temperature substantially the same as Example 9. The rotational speed of the disk was increased to 1190 r.p.m. giving a peripheral velocity of 20.6 ft./ sec. and the depth of insertion into the melt was reduced to 2 mils. The filament produced had a cross section of approximately 2 mils x 12 mils and a length of .9 inches.

Example 11 The same disk was used as in Examples 9 and 10 to produce filament of nodular cast iron. The disk was rotated at 3200 r.p.m. yielding a peripheral surface velocity of 55.5 ft./sec. 2 mils below the surface of a molten pool of nodular cast iron at 2700 F. The disk operated at a temperature initially of 75 F. and still produced filament at a temperature of 600 F. The filament had the dimensions of 10 mils by 35 mils and was approximately 1 inch in length.

Example 12 Discontinuous fibers have also been produced using a disk of different dimensions. A copper disk having the following dimensions was used to produce discontinuous fiber of Manganese Steel (12.4 Mn, 1.3 C, balance Fe):

Diameter of the disk inches 8 Thickness do 1 Radius at the tip of the V do .0325 Angle of the V degrees 90 The disks V-shaped peripheral edge had the same type of indentations as Examples 9, 10, and 11 placed every inch along the circumference of the disk. It was rotated 1 l at 550 rpm. yielding a peripheral velocity of 19.2 ft./ sec. and operated in the temperature range from 150 F. to 440 F. The manganese steel melt was at approximately 2900 F. and the filaments produced had a V-shaped cross section with a 10 mil height and a 40 mil width with a length of 1 inch.

It is herein understood that although the present invention has been specifically disclosed with preferred embodiments and examples, modification and variation of the concepts herein disclosed may be resorted to by those skilled in the art and such modifications and variations are considered to be within scope of the invention and the appended claims.

We claim:

1. A method of producing solid filament from molten material which is at a temperature within 25 percent of its equilibrium melting point in K., said molten material having a viscosity of 0.001 to 1.0 poise and a surface tension of 10 to 2500 dynes/ cm. at said temperature, comprising:

(a) rotating a heat-extracting disk having an edge tapering to a narrow peripheral surface at a peripheral speed in the range of from 3 to 200 ft./sec.;

(b) introducing the peripheral edge of said rotating disk up to a depth of 0.06 inch into the surface of a pool of said molten material to form a film of said material on said edge and removing heat from said film and at least partially solidifying said film on said edge;

(c) projecting by centrifugal force said film from said disk as a filament; and

(d) cooling said filament in a surrounding atmosphere.

2. The method of Claim 1 wherein Step (b) there is deposition of an additional liquid portion of said molten material on the solid portion adherent to said disk as said disk and said partially solidified filament exit the surface of said pool.

3. The method of Claim 1 wherein said rotating heatextracting disk has multiple, adjacent, narrow peripheral edges to contact the molten material substantially simultaneously to produce multiple filaments.

4. The method of Claim 1 wherein said disk edge has a peripheral speed in the range of from five to one hundred feet per second.

5. The method of Claim 4 wherein the edge of said rotating disk rotates less than 0.060 inch below the surface of said molten material and has a tapered edge producing a filament of cross-sectional area less than 0.01 square inch.

6. The method of Claim 4 wherein said disk has a thermal capacity sufiicient to completely solidify said film before said film is projected from said disk edge.

7. The method of Claim 4 wherein said film is partially solidified before said film releases from said disk edge and is at least partially remelted subsequent to release from said disk edge by excess heat present in the molten portion of said filament.

8. The method of Claim 5 wherein solidification of said molten material is initiated at the edge of said disk by providing said edge with a V-shaped circumferential protrusion with said filament forming on the apex of said V.

9. The method of Claim 8 wherein the angle of said V-shaped protrusion is in the range of 60' to 120 degrees and the radius of curvature at the apex of said V is in the range of from 0.001 to 0.10 inch.

10. The method of Claim 9 wherein said disk edge has at least one indentation and the depth of said disk into said molten material is less than the depth of said indentation thereby producing a plurality of filaments each having a length equal to the distance along the edge of said disk between said indentations.

11. A method for producing a solid filament from molten ferrous metal comprising:

( introducing an edge of a rotating heat-extracting 12 disk into the surface of a pool of molten ferrous metal said circumferential edge having a substantially V-shaped cross section, the sides of which form an angle from 60 to 120 and having a radius of curvature at the tip of said V being in the range of from 0.001 to 0.10 inch;

(b) rotating said disk at a peripheral speed of 5 to ft./sec.;

(c) maintaining a depth of immersion of said edge into said molten ferrous metal from just contacting the surface up to 0.060 inch below the surface to form a film of metal on said edge; and

(d) forming a filament of said metal by releasing said metal from said edge primarily under the effect of centrifugal force from said pool and said rotating disk while continuing the cooling of said filament in a cooling atmosphere adjacent said disk.

12. The method of Claim 11 wherein said rotating heatextracting disk has multiple adjacent peripheral edges to contact said molten ferrous metal substantially simultaneously to produce multiple filaments.

13. The method of Claim 12 wherein at least one of said multiple edges is formed with spaced indentations and said edge is immersed into the surface of said molten ferrous metal to a depth that is less than the depth of said indentations so as to produce predetermined lengths of filaments.

14. The method of Claim 4 wherein solidification is initiated at the edge of said heat-extracting disk on a radius of curvature of said disk edge less than 0.5 inch and said disk edge is inserted into said molten material at a depth of less than 0.020 inch.

15. The method of Claim 14 wherein said edge has at least one indentation and the depth of insertion of said disk into said molten material is less than the depth of said indentation thereby producing a plurality of filaments each having a length equal to the distance along said edge between said indentations.

16. The method of Claim 4 wherein said molten material is selected from the group consisting of metals and metal alloys.

17. The method of Claim 16 wherein said molten material is a metal alloy having a base metal selected from the group consisting of iron, nickel, aluminum, copper, and zinc.

18. The method of Claim 4 wherein said molten material consists of a material selected from the group of a metal, a metal alloy, and an inorganic compound.

19. A method of producing solid filament from molten material which is at a temperature within 25 percent of its equilibrium melting point in K., said molten material having a viscosity of 0.01 to 1.0 poise and'a surface tension of 10 to 2500 dynes/cm. at said temperature, com prising:

(a) rotating a heat-extracting disk having an edge tapering to a narrow peripheral surface at a peripheral speed in the range of 3 to 200 ft./sec.;

(b) introducing the peripheral surface of said rotating disk to the surface of a pool of said molten material;

(c) raising said rotating disk edge above the equilibrium surface level of said pool while creating a buildup of molten material at said surface between said disk edge and said equilibrium surface by surface tension and passing said edge through said buildup of molten material above said equilibrium. surface and forming a film of said material on said edge by removing heat from, and partially solidifying said film on said edge;

((1) projecting by centrifugal force said film from said disk as a filament; and

(e) cooling said filament in a surrounding atmosphere.

(References on following page) References Cited UNITED FOREIGN PATENTS 623,005 5/ 1949 Great Britain.

STATES PATENTS Kratz 264215 ROBERT F. WHITE, Primary Examiner 132132? 33:33:33: ifiiiii 5 HALL, Assistant Examiner Lawrence et a1. 264-215 Howes et a1. 264--Dig. 19 Battigelli 264Dig. 19 16484, 87, 283M; 264-165, 311

Glazer 264-215 10 

